And according to the EPA, school buses may have a lot to do with that ground pollution. A school bus can emit nearly twice as much pollution per mile as a semi-truck, and it doesn't help that the kids who ride them, with their younger and developmentally sensitive respiratory systems, typically take in more breaths than adults.

That's why the state is offering to foot the bill for ditching old diesel-engine vehicles and replacing them with new hybrid or alternative fuel vehicles -- and why the state is looking toward Dallas as a prime candidate.

The program is called the Texas Clean Fleet Program, and it's a grant under the umbrella of the Texas Commission on Environmental Quality (TCEQ). Any business, school district, government entity, or rig hoarder with at least 75 diesel vehicles can apply for the grant. The organization must be planning to replace at least 20 vehicles, and can replace all the vehicles, with hybrid ones.

Only areas where ground ozone levels desperately need reducing are eligible. According to the TCEQ, Dallas is listed listed a "nonattainment area," or a region where local emission levels have failed to meet federal standards (although we've pretty much routinely violated the Clean Air Act for the past seventeen years).

Dallas County Schools is the 4th largest provider of school buses in the country, serving 11 districts in the area -- and most of these vehicles run on diesel fuel. Replacing Dallas County Schools' diesel buses could have a huge impact on helping Dallas reach federal clean air compliance standards.

"The grant status is for counties for the ground level ozone to reach attainment," Joe Walton, spokesman for the Texas Emissions Reduction Program with TCEQ, told Unfair Park. "We focus on these areas and other counties [that are] approaching nonattainment."

"It incentivizes going from older, dirtier diesel engines to cleaner engines," says Walton. And it incentivizes Dallas County Schools to replace their yellow bus jalopies with shiny, new, environmentally-friendly transportation. Not to mention make cleaner breathing air for roughly 425,000 area students.

Walton says that he expects about half the grant applicants to be school districts. If you're picturing a fleet of Prius school buses, though, think again. The TCEQ will only fund 80 percent of the replacement costs, and it's up to the grant recipients to pay the remaining cost.

"We have already starting looking into this grant to see if we qualify and how many vehicles we will have the opportunity to replace," David Escalante, a spokesman for Dallas County Schools, which operates buses for DISD and other county districts, told Unfair Park in an e-mail. "This grant would help to replace the older diesel engine buses and help reduce the amount of nitrogen dioxide (NOX) emissions that they put into the atmosphere compared to the cleaner new diesel buses."

Walton concurs that the grant would be an help reduce NOX emissions produced by the thousands of metroplex school buses, which are both harmful to the ground level ozone layer and to childrens' developing respiratory systems. He says that previous emission reduction programs have had some effect on DFW emission levels. "Emissions are cleaner in Dallas than they have been in past years," he said. "So these programs do have an effect."